I would suggest breaking the thoughts down step by step in each situation and challenging the thoughts in your own mind..."I feel guilty because I set a boundary with ________ which I had a right to do because boundaries help people to feel safe. If I ignore boundaries, that is not good for me or for _______ so I am doing the right thing here. If ________ is not okay with my limits, then that is for him/her to deal with on their own time. I'm not going to spend more time thinking of it. Instead I will go and _______ (whatever brings you comfort or joy)"

Perhaps it could help you to investigate the roots of your guilt. Hint: the person(s) who raised you. Is/was guilt a factor in that relationship? An experienced therapist could be really helpful there.

When I am struggling with an unpleasant or confusing feeling, I find guided meditation very helpful. If you are interested, you can try going to YouTube with a search for 'guided meditation for dealing with guilt' or 'guided meditation for empowerment.' Lots of wonderful options.